Mark Spreitzer was sworn in as the State Senator for the 15th Senate District on January 3, 2023. He previously served as the State Representative for the 45th Assembly District from January 2015-January 2023. From November 2016-March 2022, Mark served as the Assembly Democratic Caucus Chair. 

During the 2023-2024 legislative session, Mark serves on the following six committees in the Senate: 


Prior to serving in the State Assembly, Mark served on the Beloit City Council from April 2011 until April 2015, and served as Council President from April 2014 until April 2015. He also worked in the Alumni Office for his alma mater, Beloit College.

Mark is an active member of the community and participates in nonprofit and community organizations, including serving as the Board President of the Welty Environmental Center and on the Finance and Facilities Board of the United Church of Beloit. He previously served on the board of Community Action Inc. of Rock and Walworth Counties.

Mark lives in Beloit with his husband, Philip, and their cat, Otis. They enjoy camping and hiking, cooking and baking, and spending time with their families - including their young nieces and nephews. Mark spends his free time enjoying the outdoors and attending events across the 15th District.